Caltrans contractors continue to work on the seismic safety project under the Dumbarton Bridge that's schedule to close Friday night at 10pm, reopening to the public at 5am Tuesday May 29th. Photo taken on Wednesday, May 23, 2012 in Menlo Park Calif.

Photo: Lance Iversen, The Chronicle

Caltrans contractors continue to work on the seismic safety project...

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In May, crews prepare to shut the bridge over Memorial Day. The bridge was closed a second time this weekend.

Good weather aided crews working on upgrades intended to protect the Dumbarton Bridge from earthquakes, and Caltrans officials said the span is expected to open on schedule for the Tuesday morning commute - or possibly even earlier.

"The weather has been great, and we've been able to get a lot of work done," Caltrans spokesman Bart Ney said Sunday. "We are on track with all the seismic retrofitting ... and we've been able to get lots of maintenance done. It's an added benefit - we are doing months, if not a year's, worth of work."

The bridge was shuttered to traffic around 10 p.m. Friday, and crews have been working around the clock to replace the existing expansion joints on its eastern side. Seismic work on the western side was completed over Memorial Day weekend earlier this year.

Ney said traffic has been flowing smoothly in the areas around the span, which connects Newark in the East Bay with Menlo Park on the Peninsula.

On Sunday, Ney said, workers finished placing 12 support plates and poured concrete; they also managed to clean up 25 cubic yards of litter, mow 12 acres of land, replace and paint the crash barrier at the toll plaza, and replace 300 feet of fence.

The span will open by its scheduled time at 5 a.m. Tuesday, Ney said, and "there's a possibility it could open early."

In the meantime, drivers should take Highway 237 to the bridge's south, or use the San Mateo Bridge to its north.